Using two half-bridge drivers in H-bridge circuit

[Dlibip6]

Hi,
I wanted to use cheap and available in store a half-bridge Driver IR2104. I don't get, how to make it works. Do I need two PWM signals, phase of the second is 180 compared to first one?

I will use the H-bridge to control Peltier.

 

[danadak]

Generally speaking you use a pwm that generates gate signals that look like -


Where the above show "dead time" between phases to operate bridge.
You basically drive one leg low, the other high, and vice versa. At no time are
both devices in one leg on, otherwise you have a dead short on power supply.

Can use two pwms or one (prevalent these days) with multiple compare registers.

Regards, Dana.

 

[Dlibip6]

Do I need dead time on N-Ch mosfets, when I operate in one direction? To change polarization I can set delay.

EDIT
I found a project instructables.com and still wondering how it is possible to work. Look at his code.

EDIT
I would put logic 0 on right driver of H-bridge and PWM signal on left for normal polarization.

 

[danadak]

As long as you do not turn on both fets in vertical leg you are good to go.


Regards, Dana.

 

[Dlibip6]

danadak
I've built this similar circuit without D2,D4,D8,D9. I tested it on without PWM, just constant voltage, high on one side IR2104 and low on the opposite side IR2104.

There are DIT150N03 with low RDS(on) in my PCB. It worked but one mosfet got hot. The load was around 100W. They all have tiny radiators.

Can IR2104 be used while providing constant signals ?

 

[ronsimpson]

Can IR2104 be used while providing constant signals ?

No! It needs the MOSFETs to switch to store energy for the top Gate Driver to work.

 

[Dlibip6]

Thanks. Now it worked fine. Could you recommend minimal and maximal duty cycle when frequency is 62.5kHz?
I would like to go from 1% or less and have the top Gate Driver worked. I don't see any info in dastascheet about minimal tON.

In addition. The H-bridge with maximum load.

 

[ronsimpson]

I did not see the minimum duty cycle in the data sheet. Some other gate drivers give a number. I think 1% is very low.
There is another way to power the top gate drivers, but it takes more parts.